1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a method for manufacturing the same, an electrophotographic apparatus and a process cartridge having the electrophotographic photosensitive member, and a hydroxygallium phthalocyanine crystal.
2. Description of the Related Art
As a charge generation material for use in the electrophotographic photosensitive member, a phthalocyanine pigment having high sensitivity is used.
However, while the electrophotographic photosensitive member containing the phthalocyanine pigment has an excellent sensitivity characteristic, a photomemory effect is likely to occur due to stray light coming from the outside of the process cartridge or the electrophotographic apparatus, and thus the improvement thereof has been demanded in recent years. The photomemory effect is a phenomenon caused by carriers that stay in a portion irradiated with light (irradiated portion), and thus arise a potential difference between the irradiated portion and a portion which is not irradiated with light (non-irradiated portion). As a result, the phenomenon causes a reduction in image quality (image reproducibility).
Japanese Patent Laid-Open No. 5-249716 describes that, by the use of a hydroxygallium phthalocyanine crystal for an electrophotographic photosensitive member, the electrophotographic photosensitive member exhibits high sensitivity to near-infrared light from a semiconductor laser and excellent stability when repeatedly used. Moreover, Japanese Patent Laid-Open No. 2005-290365 describes a technique of providing an electrophotographic photosensitive member with high sensitivity and low environmental dependence by the use of a phthalocyanine composition containing two kinds of phthalocyanine compounds.
However, as a result of an examination of the present inventors, the photomemory effect has not been sufficiently suppressed by the techniques described in Japanese Patent Laid-Open Nos. 5-249716 and 2005-290365.
The present invention provides an electrophotographic photosensitive member which suppresses the photomemory effect, a method for manufacturing the same, an electrophotographic apparatus, and a process cartridge having the electrophotographic photosensitive member.
Furthermore, the present invention provides a novel hydroxygallium phthalocyanine crystal of a crystalline form having a specific peak at Bragg angle in CuKα characteristic X-ray diffraction.